YES Problem: f(s(x),y) -> f(x,s(x)) f(x,s(y)) -> f(y,x) f(c(x),y) -> f(x,s(x)) Proof: Matrix Interpretation Processor: dim=1 interpretation: [c](x0) = 3x0 + 3, [f](x0, x1) = 4x0 + 2x1 + 3, [s](x0) = 4x0 + 6 orientation: f(s(x),y) = 16x + 2y + 27 >= 12x + 15 = f(x,s(x)) f(x,s(y)) = 4x + 8y + 15 >= 2x + 4y + 3 = f(y,x) f(c(x),y) = 12x + 2y + 15 >= 12x + 15 = f(x,s(x)) problem: f(c(x),y) -> f(x,s(x)) Matrix Interpretation Processor: dim=3 interpretation: [1 1 1] [1] [c](x0) = [1 1 1]x0 + [1] [1 0 0] [0], [1 1 1] [1 1 0] [1] [f](x0, x1) = [0 0 0]x0 + [0 0 0]x1 + [0] [0 0 0] [0 0 0] [0], [1 0 0] [0] [s](x0) = [1 1 1]x0 + [1] [0 0 0] [0] orientation: [3 2 2] [1 1 0] [3] [3 2 2] [2] f(c(x),y) = [0 0 0]x + [0 0 0]y + [0] >= [0 0 0]x + [0] = f(x,s(x)) [0 0 0] [0 0 0] [0] [0 0 0] [0] problem: Qed